When Abby Fagerlin tried logging into Canvas, a popular educational technology platform, to check on her assignments Monday morning, she couldn’t get in.

That meant the 19-year-old college sophomore, who is studying physics at Pasadena City College, was unable to access materials she needed for her three classes, which were hosted on or linked through the learning management system. After searching online, she realized the Amazon Web Services outage that crippled much of the internet Monday had also temporarily taken down Canvas.

Fagerlin also couldn’t be sure if she’d missed a message from her professors—some of whom she said communicated exclusively with their students through a messaging system hosted on Canvas. Going to talk to one of her professors to ask for physical materials from his class, meanwhile, posed a separate challenge.

“His office hours are [posted] on Canvas,” she said.

It wasn’t just Fagerlin having problems. More than a dozen students at colleges and universities across the country told WIRED the Canvas outage threw off their schedules, preventing them from not just submitting and viewing assignments but also from participating in-class activities, contacting professors, and accessing the textbooks and other materials they need to study.

The hit to Amazon’s sprawling cloud computing services meant sites and platforms like WhatsApp, Venmo, ChatGPT, Roblox, Snapchat, Signal, and even some UK banks were inaccessible to some users Monday. The outage stemmed from AWS’ northern Virginia hub, called US-EAST-1. By Monday evening eastern time, Amazon said all AWS services had been restored.

But the disruptions to students are a testament to just how popular Canvas is on college campuses—and how much of modern educational life is increasingly centered on a handful of educational technology platforms.

Canvas is one of the leading web-based learning management systems used by schools and universities across the country, competing with other platforms like Blackboard and Moodle. According to figures provided to WIRED by Brian Watkins, the director of communications at Instructure, the company which owns Canvas, half of college and university students across the US use Canvas, while 38 percent of K-12 students also use the software.

Watkins told WIRED in a statement that Instructure “recognize[s] the integral role Canvas plays in the daily lives of educators and students, serving as a central hub for teaching and learning, and we acknowledge the significant impact today’s Amazon Web Services (AWS) outage had on that experience.”